Investments (Details Textuals 12) (USD $) In Billions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss)
Carrying Value of investments accounted for under the equity method	$ 10.6
Unfunded commitments for investments accounted for under the equity method	3.0
Total assets for investments accounted for under the equity method	285.2	266.4
Total liabilities for investments accounted for under the equity method	28.8	31.2
Net Income (loss) for investments accounted for under the equity method	$ 17.9	$ 9.7	$ 18.7
Aggregate Net income Exceeded Stated Percentage Of The Pre Tax Income (Loss) From Continuing Operations	10.00%